This invention relates to a process for the preparation of dihydroaromatic hydrocarbons. More particularly, this invention relates to the electrolytic reduction at the cathode of aromatic hydrocarbons in an aqueous emulsive electrolysis medium in an undivided electrolytic cell to yield the corresponding dihydroaromatic hydrocarbons.
The electrolytic reduction of aromatic hydrocarbons to the corresponding dihydroaromatic hydrocarbons is known in the art. As known processes for effecting this transformation, there are exemplified the following:
(1) A method for electrolytically reducing aromatic hydrocarbons to the corresponding dihydroaromatic hydrocarbons in a divided electrolytic cell by subjecting an organic solvent free catholyte composed of a heterogeneous mixture of such aromatic hydrocarbon and an aqueous solution of one or more quaternary ammonium salts to electrolysis at a temperature from 30.degree. C. to 100.degree. C. This process is described in Hatayama et al, U.S. Pat. No. 3,700,572.
(2) A process for electrochemically reducing aromatic compounds in the presence of an aqueous system containing an amine, an inorganic acid or the ammonium salt thereof, and an electron deficient compound soluble in the amine, such as boron trifluoride, preferably in an undivided electrolytic cell to yield the corresponding dihydroaromatic hydrocarbon, this process being described in Matthews, U.S. Pat. No. 3,684,669.
(3) A process as described in Matthews, U.S. Pat. No. 3,682,791 for electrochemically reducing aromatic compounds in the presence of a substantially anhydrous system containing an amine, an inorganic acid or the ammonium salt thereof, and an electron deficient compound soluble in the amine, such as boron trifluoride, preferably in an undivided electrolytic cell.
(4) A process for electrochemically reducing aromatic compounds in the presence of an amine, an inorganic acid or ammonium salt thereof, and a hydrophobic quaternary ammonium salt, which process is disclosed in Matthews, U.S. Pat. No. 3,682,794.
(5) A process for electrochemically reducing aromatic compounds in the presence of anhydrous methylamine (and other low molecular weight amines such as ethylamine, ethylenediamine, or the like) containing lithium chloride in an undivided cell to yield the corresponding dihydroaromatic compounds, which process is described in Benkeser et al, Journal of the Amerian Chemical Society, 86, 5272-5276 (1964).
These and other prior art processes, however, have various drawbacks, such as requiring divided electrolytic cells, complex electrolysis media, anhydrous conditions, or some combination thereof, none of which are conductive to economical commercial development.
Thus the present process, whereby the electrolytic reduction of aromatic hydrocarbons to yield dihydroaromatic hydrocarbons is effected in a simplified and aqueous emulsive electrolysis medium in an undivided electrolytic cell, is a decided and useful advance in the state of the art.